Transport system

ABSTRACT

A method for controlling a variable speed transport system for moving a plurality of documentary items at a predetermined speed, acceleration and deceleration the method comprising: determining a mass of each pack of documents; using the determined mass to determine a maximum speed, acceleration and deceleration; and adjusting the predetermined speed acceleration and deceleration in dependence upon the determined maximum speed, acceleration and deceleration.

FIELD OF THE INVENTION

The present invention relates to a transport system for a paper handling apparatus, such as is used for preparing mass mailings.

A typical such paper handling apparatus transports documents between various processing modules such as printing stations, sheet separator modules, folding modules, collating sections and finally to an inserter which stuffs them into envelopes for mailing. Typically a letter will be printed and collated with one or more items of insert material such as information leaflets, advertising flyers, return envelopes and rates cards all stored in different feeder hoppers. The letter or insert material may be a single sheet or multiple sheets from the same hopper or from a number of different hoppers and each is known as a document pack. One or more document packs are collated into a document group for insertion into an envelope.

It is desirable to transport items such as the document packs and groups at the maximum speed but this is limited by the mechanical and electrical capabilities of the system, particularly in sections where document packs and groups need to be accelerated from rest to a maximum constant speed and then decelerated to rest again. The inventor has recognised that the mass of the document packs and groups being transported at any time influences the maximum speed, the maximum acceleration and the maximum deceleration that can be achieved and the invention takes this into account.

When a document pack or group is always the same size, i.e. comprises the same number and types of sheets of paper, then its weight is fixed and a maximum speed can be chosen to be comfortably within the system constraints. However any one machine is often used to transport and assemble different sized packs and groups of documents even within the same job. For example, a job concerning bank statements typically entails accumulating, folding and transporting all pages belonging to the same customer. One customer may have a single page statement and another may have a forty-page statement. Hence the mass of packs of documents within the same job will vary, sometimes considerably. Generally speaking, for reliable paper handling and machine operation, the optimum speed, acceleration and deceleration for heavy items will be lower than that for light items. If lower values of speed, acceleration and deceleration are chosen to accommodate the heaviest item then the overall through-put will be correspondingly reduced. Larger drives and mechanisms may be used to transport the heavy items at higher speeds but with attendant cost.

SUMMARY OF INVENTION

There is provided a method for controlling a variable speed transport system in a paper handling apparatus for moving a plurality of packs of document items, the method comprising: determining a mass of each item; using the determined mass to derive a maximum speed of transport for each item; and adjusting the speed of transport in dependence upon the determined maximum speed wherein the mass of each item is determined from a setting of a separator module in the paper handling apparatus.

According to a preferred embodiment the determined mass is also used to determine a maximum acceleration or deceleration rate, or both, for the item, and the method adjusts the acceleration or deceleration rate, or both, for the item.

The mass of each item may be determined in several ways. It may be manually input by an operator setting up the job. Alternatively the operator may enter parameters from which the system can calculate the mass, for example the dimensions and density of the whole item or of individual constituent sheets of the item and the number of sheets making up the item.

In one example the mass of an item (pack or group) is deduced from “intelligent” information held as a barcode or other optical marks on one constituent of the pack being assembled, such as on the first page of a letter which is known as the prime document. Such optical marks are often used to govern the feeding of the appropriate number of sheets for a pack and/or the appropriate inserts to be included in the group.

In another embodiment the mass of each different item may be predetermined by the system job selection, for example from the settings applied to sheet separator modules which separate sheets loaded in the hoppers. A weighing module could alternatively or additionally be incorporated to measure the actual mass of each pack.

The maximum speed, acceleration or deceleration of transport for each item (pack or group) can be determined by calculation or by using a look-up table, and will preferably take into account mechanical and electrical characteristics of the system.

According to a second aspect of the invention there is provided a corresponding variable speed transport system.

For a better understanding of the present invention and to show how the same may be carried into effect reference will now be made to the accompanying drawing in which the single FIGURE is a diagrammatic representation of a transport control system according to the present invention.

The FIGURE shows a user interface 1, which may for example be a PC keyboard or touch sensitive screen, via which instructions and settings can be entered into the system. The instructions will generally fall into two categories: machine configuration instructions 2 and job configuration instructions 3. The machine configuration instructions 2 will typically include the number and type of modules making up the apparatus being controlled by the system, and details of the module capabilities such as maximum speed, capacity and size. The job configuration instructions 3 typically include details of document properties, i.e. of the number and type of sheets or other documents to be accumulated in a relevant cycle of the job, as well as the required module behaviour, such as the fold type to be employed. The machine and job configuration settings are used in a machine control section 4 to derive settings for the modules and for transport between the modules.

The machine control section 4 performs real time machine control and document tracking via an electrical interface 5 which monitors and drives sensors 6, solenoids 7, interlocks 8 and motor drives 9. These control a variable speed mechanism 10 for the transport sections between the modules of the apparatus. A typical transport section is shown at 11 and comprises a conveyer belt 12 driven around two spaced pulley wheels 13 and 14. Pawls 15 and 16 are fixed to the conveyer belt 12 and pawl 15 is shown pushing a document pack 17 in the direction of arrow 18.

According to the invention the job configuration instructions 3 will also include the mass of each item to be transported, or properties allowing the mass to be calculated or otherwise deduced or generated.

Using the interface 1, the operator can enter details of the dimensions and density of sheets and/or of other documents to be transported between modules and assembled in the apparatus. The system can then use these details, in conjunction with information on the make-up of an item (pack or group), to calculate the mass of any item. This calculation is shown schematically at 19 in the machine control section 4. The mass is then used to derive a maximum safe speed, acceleration and deceleration for transport of the item between the modules as shown schematically at 20 in the machine control section 4.

In one example the mass of an item can be calculated from the settings of a separator module used to separate the items loaded in a hopper. This setting may be entered as a job setting by the user or deduced by means of sensor inputs and can be used to calculate or deduce the thickness of the items in the hoppers.

The item width and length may be entered as job settings by the user or deduced by means of sensor inputs or assumed (i.e. sizes most typically used in that part of the world. For example, the most common sheet size in Europe is A4).

The item density may be entered as a job setting by the user or assumed, again say the most typically used in that part of the world.

The software then calculates the weight of a single item from weight=length×width×thickness×density.

Determining the optimum speed, acceleration rate and/or deceleration rate for transport of an item between modules of the system for any given item mass can be done by mathematically modelling the transport system in a manner which is known to persons skilled in the art of such modelling.

However it can also be achieved, more easily, by limit testing the performance of the system under various load conditions, i.e. for different item masses, and storing the results in a table. Measurement points must be chosen carefully to characterise the performance with sufficient resolution. One example is given below for a system used to transport between 1 and 50 identical A4 sheets at any one of six discrete predetermined speeds S1 to S6, with an acceleration rate chosen from three discrete predetermined values A1 to A3 and likewise a deceleration rate chosen from three discrete predetermined values D1 to D3.

A typical procedure would involve running the apparatus to populate the following table:

Max ‘safe’ Max ‘safe’ Max ‘safe’ Document speed acceleration deceleration load Equivalent setting setting setting (sheets) weight(g) S A D 1 5 10 50 20 100 30 150 40 200 50 250

A typical procedure would involve the following steps:

-   -   1. Load the system with a single sheet     -   2. Set the speed to the minimum value, 1 in this case     -   3. Set the acceleration to the minimum value, 1 in this case     -   4. Set the deceleration to minimum value, 1 in this case     -   5. Run the system over a sufficient number of cycles to         ascertain that the document mass can be transported reliably and         repeatedly without any undesirable outcomes like damage to the         document, motor stalls or any other unwanted effect.     -   6. Increment the acceleration one step at a time and determine         the maximum ‘safe’ acceleration setting for correct operation.         Record this value in the table     -   7. Increment the deceleration one step at a time and determine         the maximum ‘safe’ deceleration setting for correct operation.         Record this value in the table     -   8. Increment the speed one step at a time and determine the         maximum ‘safe’ speed value for correct operation. Record this         value in the table.     -   9. Repeat steps 2 to 8 for the remaining document load values in         the table.

Once the table is complete the values from the table are programmed into the system control software as a system characteristics data table. Then during operation of the system, and before starting each move of an item, the machine control software would:

-   -   1. Determine the mass of documents from the machine and job         configuration data and knowledge of the number and type of         documents that make up an item     -   2. Use this mass to lookup the safe value of acceleration,         deceleration and speed that can be used for transporting this         mass from the system characteristics data table. For example,         the if the mass was determined as 130 g, the software would use         the acceleration, deceleration and speed values stored against         the closest FIGURE, i.e. against 150 g.

The machine control software would then apply (write) these values to the electrical interface and start the move of that item.

The whole process would then be repeated for the next move of the same item and of the next item. 

1. A method for controlling a variable speed transport system in a paper handling apparatus for moving a plurality of packs of document items, the method comprising: determining a mass of each item; using the determined mass to derive a maximum speed of transport for each item; and adjusting the speed of transport in dependence upon the determined maximum speed wherein the mass of each item is determined from a setting of a separator module in the paper handling apparatus.
 2. A method according to claim 1 further comprising using the determined mass of each item to derive a maximum acceleration rate for each item and adjusting the acceleration rate of an item in dependence upon the determined maximum acceleration rate.
 3. A method according to claim 1 further comprising using the determined mass of each item to derive a maximum deceleration rate for each item and adjusting the deceleration rate of an item in dependence upon the determined maximum deceleration rate.
 4. A method according to claim 1 wherein the separator module setting is determined by weighing each pack.
 5. A method according to claim 1 wherein the separator module setting is determined by weighing each document.
 6. A method according to claim 1 wherein the separator module setting is determined by manual input of the mass of each of the items.
 7. A method according to claim 1 wherein the separator module setting is determined by manual input of the dimensions of the item.
 8. A method according to claim 1 wherein the separator module setting is determined by manual input of parameters identifying the type of document in the item.
 9. A method according to claim 1 wherein the derivation of the maximum speed of transport of each item is dependent upon document tracking information from sensors.
 10. A method according to claim 2 wherein the derivation of the maximum acceleration rate of each item is dependent upon document tracking information from sensors.
 11. A method according to claim 3 wherein the derivation of the maximum deceleration rate of each item is dependent upon document tracking information from sensors.
 12. A variable speed transport system for moving a plurality of document items in a paper handling apparatus, the system comprising: a module for determining a mass of a document item from a setting of a separator module in a paper handling apparatus; a module for using the determined mass to derive a maximum speed for that item of transport; and a module for adjusting the speed of transport of that item in dependence upon the derived maximum speed.
 13. A transport system according to claim 12 further comprising: a module for using the determined mass of an item being transported to derive a maximum acceleration rate for that item; and a module for adjusting the acceleration rate of that item in dependence upon the derived maximum acceleration rate.
 14. A transport system according to claim 13 further comprising a module for using the determined mass of an item to derive a maximum deceleration rate for that item and a module for adjusting the deceleration rate of that item in dependence upon the derived maximum deceleration rate.
 15. A transport system according to claim 13 further comprising sensors for obtaining document tracking information from at least one item being transported.
 16. A document handling apparatus comprising a transport system according to claim 13, the apparatus further comprising: a hopper for storing documentary items to be transported; a separator module for taking items individually out of the hopper; a control for adjusting a setting of the separator module; and a module for determining the mass of the item in the hopper from the setting of the separator module. 